This invention generally relates to garment cleaning apparatuses, and is specifically concerned with a water wash apparatus for both washing the garments worn by maintenance personnel in nuclear power facilities, and radioactively decontaminating them.
Machines for cleaning radioactively contaminated clothing are known in the prior art. Such prior art machines may use either a dry cleaning technique or a water wash technique to achieve the desired end. Of the two techniques, dry-cleaning with the use of fluorocarbon solvents such as freon is presently preferred over known water wash type machines due to the generally superior penetrating ability of fluorocarbon solvents. However, before the relative advantages and disadvantages of these two types of machines can be fully appreciated, some background as to the nature of the clothing cleaned and the environment wherein it is used is necessary.
Present-day nuclear power facilities require various maintenance and operating personnel to work in areas which may be contaminated with radioactive particles. To prevent these radioactive particles from coming into contact with the skin of such personnel, protective clothing in the form of frocks, hoods, and shoe coverings (known as "duck feet" in the art) are worn. After use, it is essential that the clothing be cleaned in such a way that removes substantially all of the radioactive particulates, and all or at least most of the conventional soils, sweats and body salts than can also accumulate therein. The removal of certain rare but highly radioactive particulates, such as the "fuel fleas" which can be generated by the cracking of a fuel rod, is particularly important as such particles are capable of exposing a small, pinpoint area of skin to a dangerous level of radioactivity. However, the cost of performing such a cleaning must be substantially less than the cost of replacing the garment if it is to be cost-effective. If the cost of cleaning approaches the cost of disposing of the old garment and replacing it with another, then garment replacement becomes preferable to garment cleaning.
Dry-cleaning techniques for cleaning such radioactively contaminated clothing are generally preferred over water wash techniques due to the inherently lower surface tension and hence generally superior penetrating ability of the fluorocarbons used in such techniques. While the use of such fluorocarbons has proven effective in removing substantially all of the radioactive particulates from such clothing, such dry-cleaning techniques are not without shortcomings. For example, the fluorocarbons used in such dry-cleaning techniques tend to dissolve the elastomers in certain synthetic rubbers that form parts of boots and other shoe coverings used in maintenance operations. The dissolution of these elastomers causes the synthetic rubbers to become brittle and crack, thereby damaging and ultimately destroying the particular article of clothing containing the synthetic rubber. Other materials used in protective gloves and shoes such as Neoprene.RTM. tend to soak up and absorb the fluorocarbons used until unacceptable levels of these fluorocarbons build up in the articles of clothing. While the excess fluorocarbons might be evaporated out of the clothing by the application of additional amounts of heat, such extra or protracted steps in the cleaning process adds to the overall expense of cleaning, and may tend to heat damage the plastic and rubber portions of the clothing, thereby defeating the purpose of the extra dry-out. Still another shortcoming associated with dry-cleaning techniques is the limited ability of fluorocarbons to dissolve sweat and body salts. While the fluorocarbons may succeed in removing substantially all of the radioactive particulates, the accumulation of such sweat and body salts will ultimately give the garment a cumulative "locker room" odor. Moreover, the fluorocarbons used in such dry-cleaning techniques presently cost about $13.00 per gallon, which is not an inconsiderable expense where many gallons are required. Finally, the fluorocarbons used in these techniques are limited (as are most organic solvents) in their ability to dissolve and remove radioactive contaminants in the form of metallic salt, such as cesium 137.
While wet washing techniques avoid many of the shortcomings associated with dry-cleaning techniques in that they are highly effective in dissolving and removing sweat and body salts as well as salts of cesium 137, they, too, have their drawbacks, the most serious being the generation of a water effluent which contains the radioactive particles removed from the clothing. The transportation and disposal of such an effluent significantly contributes to the cost of the wash notwithstanding the fact that the effluent qualifies as a low radiation level waste. While most nuclear facilities have on-site demineralizer systems which are capable of radioactively decontaminating such water, the inconveniences and expenses associated with the use such on-site demineralizer systems also add substantially to the overall cost of such prior art water wash techniques. Still another problem is the relatively lower efficiency of the water used in such systems in penetrating the fabrics that form such clothing and removing radioactive particulates. The relatively lower penetrating ability of water, coupled with the greater effort needed for dry-out due to its lower volatility as compared to freon, generally has the effect of increasing the time necessary to effectively water wash a contaminated garment.
Clearly, what is needed is an apparatus and method for cleaning radioactively contaminated clothing which removes all of the radioactive particulates, and cleans the clothing of sweat, body salts and radionucleide salts without damaging or destroying any of the synthetic rubbers or artificial fibers forming such clothing. Ideally, such an apparatus should be mobile to obviate the need for the transportation of radioactively contaminated garments, which would require the use of special containers and procedures. Finally, such an apparatus should be capable of quickly cleaning a large volume of such clothing at a cost which is substantially lower than the disposal and replacement costs of the garments being cleaned.